After telling us to destroy the altars and asheirot of idolaters and obliterate any trace of avodah zarah, "v'ibadtem es shemam min ha'makom ha'hu," the Torah tells us not to do the same to Hashem, "lo ta'asun kein l'Hashem Elokeichem." (12:4)
It sounds strange -- we need to be told not to go into the mikdash and start smashing things?!
Rashi explains in his first pshat that "lo ta'asun kein" is not speaking about the act of destroying things, but is a continuation of the earlier pasuk which describes the many places in which idolatry was worshipped and needs to be rooted out from -- on the mountains, in the valleys, across the fruited plains (whatever). Don't worship G-d like that, the Torah tells us. There is one central place of worship -- a beis ha'mikdash.
Sefas Emes suggests that "lo ta'asun kein" is a continuation of the end of the pasuk, "v'ibadtem is shemam." When avodah zarah is destroyed, it is gone and forgotten. Does anyone worship Zeus on Mt Olympus any more? There are a lot of crazy people in NY, but I have never heard of anyone who carves little statutes out of wood or stone and then starts bowing down to them. The avodah zarah is gone and no one even cares. Klal Yisrael is not like that. "Lo ta'asun kein" is followed by "...l'shichno tidrishu u'basa shama." Sefas Emes writes that the pasuk is not talking about when we have a mikdash, when we are living in peace in our land. It is talking about after the churban, after we have experienced destruction. We don't forget. There is no "ibud shemam" by us. "Im eshkacheich Yerushalayim tishkach y'mini." We long for the mikdash, we long for avodah.
Rashi has a second pshat in which he explains that the Torah is warning not to do aveiros that will cause the mikdash to be destroyed.
R' Sorotzkin in his Oznayim laTorah asks: the Torah in so many places warns not to do avodah zarah, not to do aveiros chamuros. These crimes have severe punishments and penalties. If that's not enough to stop people from violating those issurim, how is telling them that it will cause churban ha'bayis going to make a difference?
Just posted on hebrewbooks.org is a sefer called L'Ma'alah l'Maskil by R' Avraham Yitzchak Kook (the contemporary Rosh Yeshiva in Rechovot). He relates (p.491-492) that there was a certain R' Mordechai Weinstein who was zocheh to be meshamesh the Chofetz Chaim and who later came to live in Bnei Brak. R' Mordechai's "thing" was kedushas Shabbos. One day he hung up fliers in the Lederman shul reminding people to tell their wives to light neiros Shabbos early because otherwise they do not get credit for lighting Shabbos candles and they violate Shabbos. Apparently in Bnei Brak people are medayek even in the shul announcements. People came over and asked a kasea: obviously chilul Shabbos is far more severe than missing lighting Shabbos candles. Why on the sign did R' Mordechai first warn that the women who lit late would not get credit for lighting, and only after that mention chilul Shabbos?
R' Mordechai answered that he had a kabbalah for that specific "nusach" for his sign from the Chofetz Chaim himself years ago. And he had asked the Chofetz Chaim the same kashe everyone was asking him. The Chofetz Chaim answered that to the simple, pious women, it was unthinkable to have Shabbos without Shabbos candles. They did not know from 39 melachos, from zmanin -- they knew from Shabbos lights. So you have to speak their language. First, you have to explain that lighting after the zman was not lighting -- it was as good as no Shabbos candles. After that, after you have their attention, you can mention by-the-way, it's also chilul Shabbos.
To a Jew living b'zman ha'bays, the mikdash was his Shabbos candles. A Jew might do aveiros galore, but it would have been inconceivable to him for there not be avodah in the mikdash. You have b'zman ha'zeh, to use R' Sorotzkin's example, Jews who are mechelel everything under the sun, but then they have a baby boy and suddenly want a traditional bris milah (unfortunately even this is growing less common). This attachment to the mitzvah does not come from logic; it comes from some deep vestigial connection within the Jewish heart and soul.
The Torah therefore warns that issurim would inevitably take away the mikdash.
I hate to end on a negative note, so let me just throw in a Chasam Sofer: "l'shichno tidrishu v'basa shama," he writes, is a guarantee. If we are doresh the makom haShechina, then the result will be "u'basa shama," we will be zocheh to get there.
So we have our work cut out for us.